[RUBY] [RSpec] Let's use FactoryBot [Rails]

What is Factory Bot? ??

--A library that makes it easy to create data for testing -- ĽUse Active Record`

This and that of Factory Bot

If you install factory_bot_rails, you can create a file to create factory with the following command.

bin/rails g factory_bot:model task

I will explain a little.

Up to bin / rails g should be fine. Explicitly appear in the model with factory_bot: model. Please specify the target like task.

When you run this command, you should see a file like the following in spec / factories / tasks.rb.


FactoryBot.define do

  factory :task do


You have a template. Let's define the data in this.


FactoryBot.define do

  factory :task do
    name "Shopping"
    content "Go buy supper"

It may be less, but it should be okay. By executing FactoryBot.create (: task) in the test file, you can create the data described in spec / factories / tasks.rb.

Use FactoryBot a little.


For example, if you want to write an abnormal test that outputs an error when name of task is nil, you can write as follows.


#Invalid if there is no name.
it "is invalid without a name" do
  task = FactoryBot.build(:task, name: nil)
  expect(task.errors[:name]).to include("can't be blank")

By overwriting the property to nil, it looks as expected.

Handle unique values.

For example, the email address should be unique, it has such a specification, and you should write such a test. However, FactoryBot always refers to the same value, so it may not be possible to handle such an event.

This problem can be solved by using ** Sequence ** as shown below.


FactoryBot.define do

  factory :user do
    name "Yamada"
    sequence(:email) { |n| "test#{n}@example.com" }

By defining it like this, it will be set as [email protected], [email protected].

Very convenient.

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